Fixes for client counter

* Added discrete counter var
* Added add'l system setup steps to README
* Moved ClientCount to server (kept old code for future accuracy)
* Added fix from bbangert to clear socket channels on shutdown.
Merge branch 'mcgo' of git://github.com/jrconlin/pushgo into mcgo

Conflicts:
	src/mozilla.org/simplepush/handlers.go
	src/mozilla.org/simplepush/server.go
	src/mozilla.org/simplepush/structs.go
	src/mozilla.org/simplepush/worker.go